At

:::info[Note] This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information. :::

Returns the value at the specified key in the current ImmMap

public function at(
  Tk $key,
): Tv;

If the key is not present, an exception is thrown. If you don't want an exception to be thrown, use get() instead.

$v = $map->at($k) is semantically equivalent to $v = $map[$k].

Parameters

• Tk $key

Returns

• Tv - The value at the specified key; or an exception if the key does not exist.

Examples

See Map::at for usage examples.